Category «Rhomaleosauridae»

Plesiosaurus macrocephalus

The holotype specimen (NHMUKĀ PV R 1336) was first and last described by Owen, 1840. ‘Plesiosaurus’ macrocephalus is probably a juvenile rhomaleosaurid, and certainly doesn’t belong to the genus Plesiosaurus. However, pending revision of the taxon and referral to a different or other existing genus, it is still named ‘Plesiosaurus‘, following Owen.


Avalonnectes is a small-bodied basal rhomaleosaurid. Avalonnectes was named by Benson, Evans and Druckenmiller (2012) for a partial skeleton including the rear part of the skull from the lowermost Jurassic of Street, Somerset, UK. The specimen (NHMUK PV OR 14550) was previously referred to Thalassiodracon hawkinsii and is one of many historical plesiosaur skeletons preserved …


All rhomaleosaurids have a relatively large head with a moderately long neck composed of about 28 vertebrae. The group has a stratigraphical range from the Lower Jurassic to the Middle Jurassic. The Rhomaleosauridae is traditionally regarded as a pliosauroid family but some phylogenies place the clade outside of Pliosauroidea in a sister relationship or unresolved …